Anybody else here struggling with Japanese Knotweed?

SILVAMAN

It can be gotten rid of by using glyphosate.
Wait until the plant is 1 metre high, then cut the top off . After 5 days spray the cut surfaces. The chemical is translocated to the roots, and should do the job.

my3cents

SILVAMAN wrote: »

It can be gotten rid of by using glyphosate.
Wait until the plant is 1 metre high, then cut the top off . After 5 days spray the cut surfaces. The chemical is translocated to the roots, and should do the job.

I think that is a little over optimistic. If it was that easy I don't think this thread would exist.

SILVAMAN

my3cents wrote: »

I think that is a little over optimistic. If it was that easy I don't think this thread would exist.

It's the prescription from the foresters who run the Forest Service Native Woodland Scheme for dealing with sites that have an infestation. Spraying the planr without first cutting will effect a kill of sorts, but it will reappear.
Cutting and spraying is quite effective.
It's counterintuitive to actually cut the plant first, then spray.

NoMakerMadeMe

taxusbaccata wrote: »

Has anyone heard or tried using Lime and using heat?

I have read some USA forums where setting a large fire above the knapweed has been successful - ie the very hot soil for several hours kills the root.

Does knapweed like acidic soil? If so the lime strategy seems plausible.

My small, bounded site was being sprayed for 3 years with glyphosate before I came along.

For the first year, I dug up and burnt the main large stools (some of the thick roots seem to be growing straight to hell!!). The following year, I pulled any shoots that I could find (to starve it), as soon as they came up, stripped off the leaves, dried and burned them.

For the last 2 years, I've applied garden lime heavily in Spring and I've only seen 1 shoot in that time. I've read that JK can lie dormant for up to 20 years but I have a bad back and not much time at the moment and this certainly seems to keep it in check.

I wouldn't be allowed set a fire where I am and I don't want to use glyphosate, so I'll stick with this strategy for the time being. Apparently, cabbages love a well limed soil.

As an aside: One thing that I did notice when I started digging up the roots was that the earthworms hiding in them were huge and very lethargic.

my3cents

NoMakerMadeMe wrote: »

..... I've read that JK can lie dormant for up to 20 years but I have a bad back and not much time at the moment and this certainly seems to keep it in check.

I don't doubt it. You can definitely think you have JK beat with glyphosate and a couple of years later disturb a bit of rhizome and it will start to shout again.

I have it sort of beat after ten years on a river bank but I know if the bank erodes then the uncovered rhizome will very likely burst back to life.

ithread

its still out there arghhhhhh...

http://www.thetimes.co.uk/tto/irishnews/article4655894.ece?CMP=OTH-gnws-standard-2016_01_04

I know you might not be able to read the article (being The Irish Times and all) but just for info!

ithread

and so it begins, I've spotted it growing in one of my neighbours front gardens! It hasn't appeared in our back garden yet but should be soon! Anyone else spotted it yet?

my3cents

ithread wrote: »

and so it begins, I've spotted it growing in one of my neighbours front gardens! It hasn't appeared in our back garden yet but should be soon! Anyone else spotted it yet?

Too true! Nearly posted back here almost a month ago when I first spotted the smallest of leaves showing. I'm just hoping it was some glyphosate induced aberration that had some of mine coming up so early.

The work continues though, neighbor has about a half acre of it strimmed down this winter and ready to give it a good dose of glyphosate. Its a big area and hard to do when the plants full grown and well over 2m tall.

ithread

it all makes me shudder!

Markcheese

ithread wrote:

and so it begins, I've spotted it growing in one of my neighbours front gardens! It hasn't appeared in our back garden yet but should be soon! Anyone else spotted it yet?

Just burnt a couple of clumps of it, (on my neighbours side of the ditch) so now I can get at it to roundup it when it shoots again , but its spreading around their garden.. I only realized what it was last year.. and was quite shocked at how much of it I saw in the hedges on the road sides. ( it was obvious in autumn when the ditches were dying back , and you could see the colours of the knotweed leaves)

morebabies

Anyone have any advice re: knotweed in a polytunnel. My polytunnel has been totally invaded by it the last couple of years. After numerous sprayings with Round-up inside and outside last year, I finally thought we had got the better of it, but after leaving the polytunnel during the winter months it's back with a vengeance. I'm so disheartened, last year I had the tunnel sprayed about four times with Round-up every time I saw regrowth, but you'd think I'd been fertilizing the weed instead.
I really want to get growing veggies but I can't face more pointless battles with this weed. :-(

I should add that previous to this I covered the polytunnel soil in weed blocking fabric for about a year and a half after spraying it because I was busy with small babies . If I dug out the soil maybe and put some impermeable barrier down, then new soil on top, would that be an option?

sheesh

the method mentioned above where you cut the top and spray into the hollow of the cut stem was recommended to me by a guy in a local gardening centre, this guy would know what he is talking about too so that might be a way. some professionals use a syringe to deliver the dose I heard.

I think goats were mentioned too they nibble away at the new shoots but they might not work well with poly tunnels

impermeable barrier might not work as knot weed can grow through solid concrete

it needs repeated treatment over a number of years do not try to dig it out,

wait until it is growing vigorously use a systemic weed killer

saabsaab

Glycophosphate is the best and it will take some years to finally kill it saw 5-7 years! Old carpet over a smaller area can work too if left over it for many years. Fire is no good as this plant thrives at the base of volcanoes where it comes from.

magicbastarder

a plant thriving in volcanic soil =/= a plant is impervious to fire.

monkeynuz

Cocktail stick and syringe from vets, inject 10ml of 1:1 solution of roundup into each stem then spray 5:1 solution under the leaves then wait about ten days then clear the dead stuff out and burn it, reapply if some were missed.

dball

i dont think its recommended to burn it. Dont burn it !

morebabies

saabsaab wrote: »

Glycophosphate is the best and it will take some years to finally kill it saw 5-7 years! Old carpet over a smaller area can work too if left over it for many years. Fire is no good as this plant thrives at the base of volcanoes where it comes from.

Aagh!
5-7 years?
And it can grow through solid concrete?
This weed is pure evil. Oh man, does this mean I just find a knotweed free site for the next 7 years for growing my veg? Bye bye polytunnel?

my3cents

It won't grow through good concrete but will lift slabs and come through the tiniest gaps. In 7 years it might go dormant 20 years is more like it to kill established clumps. In a pollytunnel injecting the stems would be the best way of treatment.

saabsaab

The way it works is that it has such deep roots in the mountain that when the lava burns away the top layer it is still alive below and when the lava cools the plant pushes up through any gaps in the new formed rock above. It has evolved to work this way.
Maybe 7 years is a bit long to kill off completely but it is v tough and need repeat killing with glyco over a few years.

Markcheese

dball wrote:

i dont think its recommended to burn it. Dont burn it !

Why not burn the dead material, ? Mines(well my neighbours) just started shooting up a week ago, jeez it grows fast.. going to try the syringe trick....
Does it produce little tubers that split off ... found loads of them around the knotweed stool...

my3cents

Its doesn't produce fat tubers like say a dahlia its more of a 10-15mm thick root system that can go down a long way and spread massive distances. iirc 2m down and 22m across are the figures quoted for an established clump.

Any part of the root system can form a new plant again quoting from what I have read a broken off piece of root the size of a fingernail can create a new plant.

dball

take care if you are going to burn - I am under the impression that the spores can spark and distribute in the burning process:

more info here about JK -
Alternatively the canes can be disposed of at a licensed landfill site for deep burial via the use of a licensed waste carrier. The landfill site must be notified that the waste material contains Japanese knotweed. Alternatively, through seeking the necessary exemptions to burn, the canes maybe burnt on site. For more information on the legislation in Republic of Ireland see the following page: http://invasivespeciesireland.com/background/legislation/ireland/section-49/

yellowlabrador

morebabies wrote: »

Aagh!
5-7 years?
And it can grow through solid concrete?
This weed is pure evil. Oh man, does this mean I just find a knotweed free site for the next 7 years for growing my veg? Bye bye polytunnel?

I've got some coming in from my neighbour and i've used old duvets and carpet and grown things in growbags and pots. i mainly control it by cutting it down as soon as I see a shoot. You can maybe clear a section and start that way?

my3cents

yellowlabrador wrote: »

I've got some coming in from my neighbour and i've used old duvets and carpet and grown things in growbags and pots. i mainly control it by cutting it down as soon as I see a shoot. You can maybe clear a section and start that way?

The roots can spread over 20m underground from the central plant so covering it up might just be helping the roots cover more ground until they to shoot up?

yellowlabrador

my3cents wrote: »

The roots can spread over 20m underground from the central plant so covering it up might just be helping the roots cover more ground until they to shoot up?

I've a small back garden,it'll shoot up in the road then. Council's problem. Next door is a council house and the tenant isn't able to look after the garden. what do you do? I've been doing this for 20 years and the shoots get smaller and smaller.

Kazbah

Hi All,

I've been spraying mine but I still have regrowth - I want to pave my garden. Does JK pick the easiest path ie will it come up inbetween paving where I can keep spraying or will it damage the paving? My garden is horrendous now because I've sprayed everything and I'm waiting to get rid of JK but I wonder if I will ever get rid of it totally as my neighbouring gardens are completely covered in it and they refuse to spray. I spray over the walls when I can but their garden is overgrown wih JK. I rang the council and they said they can't do anything

Am I mad to pave?

Kaz

my3cents

Paving will be OK if you put down some sort of geo-separator. You'll find a few ideas if you google japanese knotweed geotextiles.

Edit> If its really bad you may still get some heave in the ground where is tries to come through so you paving may not stay level.

Kazbah

Thanks it's not that mad TBH - i'll google that thanks - can't cope with looking at it as it is!!

my3cents

Kazbah wrote: »

Thanks it's not that mad TBH - i'll google that thanks - can't cope with looking at it as it is!!

You'll probably find the genuine geotextiles thick enough to do the job a bit expensive but you can use more than one layer of cheaper material.

Markcheese

The neighbours stuff is already a good six foot high, (just out of my reach) ,the stuff that I could reach and spray is only a foot or so... and the bits that are speading to my side of the fence a couple of inches... is it too early to spray it....
I started noticing it everywhere on the road side...